#!/usr/bin/env python 

from operator import add, sub 
from random import randint, choice 

ops = {'+': add, '-': sub}
MAXTRIES = 2

def doprob():
	op = choice('+-')
	nums = [randint(1, 10) for i in range(2)]
	nums.sort(reverse=True)
	ans = ops[op](*nums)
	pr = '%d %s %d =' %(nums[0], op, nums[1])
	oops = 0
	while True:
		try:
			if int(raw_input(pr)) == ans:
				print 'correct'
				break 
			if oops == MAXTRIES: 
				print 'answer\n%s%d' % (pr, ans)
			else:
				print 'incorrect... try again'
				oops += 1
		except (KeyboardInterrupt, \
					EOFError, ValueError): 
			print 'invalid input... try again'

def main():
	while True:
		doprob()
		try:
			opt = raw_input('Again? [y]').lower()
			if opt and opt[0] == 'n':
				break 
		except (KeyboardInterrupt, EOFError):
			break 

if __name__ == '__main__':
	main()
